I have two directly related questions.
Django documentation recommends raising ValidationError with a code:
# Good
ValidationError(_('Invalid value'), code='invalid')
# Bad
ValidationError(_('Invalid value'))
How can I access this code in tests? All my attempts to use as_data, as_json, or simply .code on the caught exception fail. Unfortunately, the suggestions I see all relate to form validation. My test validates the models.
It is almost the same question as asked before (I don't use forms).
The related question: the same documentation page linked above gives a few examples of how to raise ValidationError, and while "Raising ValidationError" section recommends using the code, "Using validation in practice" never mentions it again, and the examples there don't use code. I wonder if that's an indication of this feature being stale.
I learned how to debug Django tests in PyCharm, and it helped me find a solution. For others' sake:
The error codes are accessible via exception.error_dict[field_name][err_no].code. For example, the following checks a very specific error is raised:
def test_negative_photo_number(self):
"""Cannot create photo with negative photo number"""
with self.assertRaises(ValidationError) as ve_context:
self.create_photo(album_number=1, photo_number=-2)
e = ve_context.exception
print(e.error_dict)
self.assertEqual(len(e.error_dict.keys()), 1, 'Encountered more than one problematic field')
self.assertEqual(len(e.error_dict['number']), 1, 'Encountered more than one error')
self.assertEqual(e.error_dict['number'][0].code, 'min_value')
For ValidationError raised outside field validators (e.g. by model.clean method), replace field name ('number' above) with __all__.
Related
I have the following QuerySet:
MyModel.objects
.order_by("foreign_key_id")
.distinct("foreign_key_id")
.in_bulk(field_name="foreign_key_id")
foreign_key_id is not unique on MyModel but given the use of distinct should be unique within the QuerySet.
However when this runs the following error is raised:
"ValueError: in_bulk()'s field_name must be a unique field but 'foreign_key_id' isn't."
According to the Django docs on in_bulk here it should be possible to use in_bulk with distinct in this way. The ability was added to Django in response to this issue ticket here.
What do I need to change here to make this work?
I'm using Django3.1 with Postgres11.
As the documentation of in_bulk(…) says:
(…)
Changed in Django 3.2:
Using a distinct field was allowed.
Since you use django-3.1, this will thus not work, you will thus have to upgrade your program to django-3.2.
Recently I found out that its possible to define Django form validation directly in the models.py file. This can be done the following way:
fev1_liter = models.DecimalField(validators=[MaxValueValidator(8.2),
MinValueValidator(0.3)],
max_digits=3, decimal_places=2)
This is an awesome alternative to validation in forms.py, but I do have a very annoying problem:
How can I control in which order the validation is executed?
In this example Django will first validate if the inputs digits is in the format x.xx and thereafter min and max value. This results in some very confusing error messages.
Thanks in advance!
For each model field, field.clean() first performs field validation via field.validate(), then via field.run_validators(), validators are called in order they are returned from the field.validators iterator.
This makes sense, because in the general case you can expect your validators to fail if the field validation failed, so it makes for easier debugging. Remember that field validators are non-obligatory, so field.validate() takes precedence. If you want to change the behavior, you'll have to create your own Field classes and override the field.clean() behavior.
You can inspect the field sources for more details.
I'm fairly new to django web development. And I got an error whereby I try to change a 'post' under admin url - so localhost:8080/admin. I'm able to create it successfully but when I try to click the post that I had just added. I'm getting this error:
Exception Type: DatabaseError Exception Value: This query is not
supported by the database.
And this is the code that I know is 'messing' with this query:
#Post is an abstract class
class BlogPost(Post):
...
translators = models.ManyToManyField(Staff, related_name='translators')
photographers = models.ManyToManyField(Staff, related_name='photographers')
authors = models.ManyToManyField(Staff, related_name='authors')
...
To explain what is going on with this blog post - it can have multiple 'owners'/people that contributed to this post and thus the decision using ManyToManyField. And vice-versa with the 'Staff' member - the type of 'member' can have multiple ownership on multiple posts (Let me know if this logic doesn't make any sense because it does to me).
I'm using mongodb for the database, django 1.5.11 and I have installed djangotoolbox. I've tried the following solutions with adding a relationship to BlogPost as shown below:
Class Staff(Member):
...
staff_posts = models.ManyToManyField(BlogPost, related_name="staff_posts")
...
But I'm getting an error on 'cannot import BlogPost'. I tried figuring out the reason of this error and I don't think that I have a circular dependance - after checking all of the files, there's no circular dependance.
MongoDB (or mongoengine, which I'm guessing you're using) doesn't support joins, so the typical way to model many-to-many relations in a relational database has to be implemented some other way.
One way is to use a ReferenceField inside a ListField. It might look like this (not tested):
class BlogPost(Post):
authors = models.ListField(models.ReferenceField(Staff))
...
Also see these answers:
https://stackoverflow.com/a/18747306/98057
https://stackoverflow.com/a/25568877/98057
Just to put it out there, I'm not real familiar with MongoDB.
However, I don't believe you need to define a ManyToManyField on your Staff class. You already have a ManyToMany defined in your BlogPost, having it defined in one class file is all that is required. (At least for MySQL).
I'm trying to set field errors in a form clean() and I'm currently doing:
self._errors['address'] = self._errors.get('address', ErrorList())
self._errors['address'].append(_(u'Please specify an address.'))
Is there a better and if possible shorter method for doing this?
New in Django 1.7 is Form.add_error( field, message ).
https://docs.djangoproject.com/en/dev/ref/forms/api/#django.forms.Form.add_error
Maybe this will help you . Its generally preferred you override clean and inside the function you could do the following
If you want to raise form specific errors you could do .
self._errors["field"] = ErrorList([u"Error"])
this is make sure you get the error class
if you have an non field error you could simple raise a validation error like so
raise forms.ValidationError(_("Error"))
Hope this helps.
Standard way is raise ValidationError(message).
Move field-specific validation to clean_<fieldname>() methods, clean_address in your case. ValidationError raised in such method will attach error message to specific field. One raised from clean() will be attributed to model in general.
I would like to know how to show personalized errors with the get_object_or_404 method. I don't want the normal Http404 pages, but I want to display a custom message with the message: the result is none.
Thanks :)
The get_object_or_404() is essentially a simple 5-line function. Unless you have some specific reason for using it, just do:
try:
instance = YourModel.objects.get(pk=something)
except YourModel.DoesNotExist:
return render_to_response('a_template_with_your_error_message.html')
If for whatever reason you have to use get_object_or_404(), you can try putting it in a try: ... except Http404: ... block, but I honestly can't think of a plausible reason for that.
As stated by michael, when using get_object_or_404 you cannot customize the message given on http 404. The message provided in DEBUG does offer information about the exception however: "No MyModel matches the given query."
Check out the doc on this. There are three arguments: Model, *args, and **kwargs. The last two are used to build an argument for either get() or filter() on the Model.
The reason I wrote, however, is to address the question of why we would want to use a helper function such as get_object_or_404() instead of, for example, catching it with an exception like Model.DoesNotExist.
The later solution couples the view layer to the model layer. In an effort to relax this coupling we can take advantage of the controlled coupling offered in the django.shortcuts module[1].
And why exactly aren't you using your server's capeability to do just that?
get_object_or_404() is redirecting to the default 404 page right?
If you are on debug mode you won't see it but when deployed django will just refer to the server's 404 html page.
That can't be done with that shortcut. It will only raise a Http404 exception. Your best bet is a try catch if you want full control. Eg.
try:
obj = Model.objects.get(pk = foo)
except:
return HttpResponseRedirect('/no/foo/for/you')
#or
return render_to_response ...